﻿/*
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at 
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *  
 */

using System;
using java = biz.ritter.javapi;

namespace biz.ritter.javapi.math
{
    /**
     * The library implements some logical operations over {@code BigInteger}. The
     * operations provided are listed below.
     * <ul type="circle">
     * <li>not</li>
     * <li>and</li>
     * <li>andNot</li>
     * <li>or</li>
     * <li>xor</li>
     * </ul>
     */
    internal class Logical {

        /** Just to denote that this class can't be instantiated. */
    
        private Logical() {}


        /** @see BigInteger#not() */
        internal static BigInteger not(BigInteger val) {
            if (val.sign == 0) {
                return BigInteger.MINUS_ONE;
            }
            if (val.equals(BigInteger.MINUS_ONE)) {
                return BigInteger.ZERO;
            }
            int []resDigits = new int[val.numberLength + 1];
            int i;

            if (val.sign > 0) {
                // ~val = -val + 1
                if (val.digits[val.numberLength - 1] != -1) {
                    for (i = 0; val.digits[i] == -1; i++) {
                        ;
                    }
                } else {
                    for (i = 0; (i < val.numberLength) && (val.digits[i] == -1); i++) {
                        ;
                    }
                    if (i == val.numberLength) {
                        resDigits[i] = 1;
                        return new BigInteger(-val.sign, i + 1, resDigits);
                    }
                }
                // Here a carry 1 was generated
            } else {// (val.sign < 0)
                // ~val = -val - 1
                for (i = 0; val.digits[i] == 0; i++) {
                    resDigits[i] = -1;
                }
                // Here a borrow -1 was generated
            }
            // Now, the carry/borrow can be absorbed
            resDigits[i] = val.digits[i] + val.sign;
            // Copying the remaining unchanged digit
            for (i++; i < val.numberLength; i++) {
                resDigits[i] = val.digits[i];
            }
            return new BigInteger(-val.sign, i, resDigits);
        }

        /** @see BigInteger#and(BigInteger) */
        internal static BigInteger and(BigInteger val, BigInteger that) {
            if (that.sign == 0 || val.sign == 0) {
                return BigInteger.ZERO;
            }
            if (that.equals(BigInteger.MINUS_ONE)){
                return val;
            }
            if (val.equals(BigInteger.MINUS_ONE)) {
                return that;
            }
        
            if (val.sign > 0) {
                if (that.sign > 0) {
                    return andPositive(val, that);
                } else {
                    return andDiffSigns(val, that);
                }
            } else {
                if (that.sign > 0) {
                    return andDiffSigns(that, val);
                } else if (val.numberLength > that.numberLength) {
                    return andNegative(val, that);
                } else {
                    return andNegative(that, val);
                }
            }
        }
    
        /** @return sign = 1, magnitude = val.magnitude & that.magnitude*/
        internal static BigInteger andPositive(BigInteger val, BigInteger that) {
            // PRE: both arguments are positive
            int resLength = java.lang.Math.min(val.numberLength, that.numberLength);
            int i = java.lang.Math.max(val.getFirstNonzeroDigit(), that.getFirstNonzeroDigit());
        
            if (i >= resLength) {
                return BigInteger.ZERO;
            }
        
            int []resDigits = new int[resLength];
            for ( ; i < resLength; i++) {
                resDigits[i] = val.digits[i] & that.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }

        /** @return sign = positive.magnitude & magnitude = -negative.magnitude */
        internal static BigInteger andDiffSigns(BigInteger positive, BigInteger negative) {
            // PRE: positive is positive and negative is negative
            int iPos = positive.getFirstNonzeroDigit();
            int iNeg = negative.getFirstNonzeroDigit();
        
            // Look if the trailing zeros of the negative will "blank" all
            // the positive digits
            if (iNeg >= positive.numberLength) {
                return BigInteger.ZERO;
            }
            int resLength = positive.numberLength;
            int[] resDigits = new int[resLength];
        
            // Must start from max(iPos, iNeg)
            int i = java.lang.Math.max(iPos, iNeg);
            if (i == iNeg) {
                resDigits[i] = -negative.digits[i] & positive.digits[i];
                i++;
            }
            int limit = java.lang.Math.min(negative.numberLength, positive.numberLength);
            for ( ; i < limit; i++) {
                resDigits[i] = ~negative.digits[i] & positive.digits[i];
            }
            // if the negative was shorter must copy the remaining digits
            // from positive
            if (i >= negative.numberLength) {
                for ( ; i < positive.numberLength; i++) {
                    resDigits[i] = positive.digits[i];
                }
            } // else positive ended and must "copy" virtual 0's, do nothing then
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = -1, magnitude = -(-longer.magnitude & -shorter.magnitude)*/
        internal static BigInteger andNegative(BigInteger longer, BigInteger shorter) {
            // PRE: longer and shorter are negative
            // PRE: longer has at least as many digits as shorter
            int iLonger = longer.getFirstNonzeroDigit();
            int iShorter = shorter.getFirstNonzeroDigit();
        
            // Does shorter matter?
            if (iLonger >= shorter.numberLength) {
                return longer;
            }
        
            int resLength;
            int []resDigits;
            int i = java.lang.Math.max(iShorter, iLonger);
            int digit;
            if (iShorter > iLonger) {
                digit = -shorter.digits[i] & ~longer.digits[i];
            } else if (iShorter < iLonger) {
                digit = ~shorter.digits[i] & -longer.digits[i];
            } else {
                digit = -shorter.digits[i] & -longer.digits[i];
            }
            if (digit == 0) {
                for (i++; i < shorter.numberLength && (digit = ~(longer.digits[i] | shorter.digits[i])) == 0; i++)
                    ;  // digit = ~longer.digits[i] & ~shorter.digits[i]
                if (digit == 0) {
                    // shorter has only the remaining virtual sign bits
                    for ( ; i < longer.numberLength && (digit = ~longer.digits[i]) == 0; i++)
                        ;
                    if (digit == 0) {
                        resLength = longer.numberLength + 1;
                        resDigits = new int[resLength];
                        resDigits[resLength - 1] = 1;

                        BigInteger result = new BigInteger(-1, resLength, resDigits);
                        return result;
                    }
                }
            }
            resLength = longer.numberLength;
                    resDigits = new int[resLength];
            resDigits[i] = -digit;
            for (i++; i < shorter.numberLength; i++){
                // resDigits[i] = ~(~longer.digits[i] & ~shorter.digits[i];)
                resDigits[i] = longer.digits[i] | shorter.digits[i];
            }
            // shorter has only the remaining virtual sign bits
            for( ; i < longer.numberLength; i++){
                resDigits[i] = longer.digits[i];
            }
        
            BigInteger result1 = new BigInteger(-1, resLength, resDigits);
            return result1;
        }
    
        /** @see BigInteger#andNot(BigInteger) */
        internal static BigInteger andNot(BigInteger val, BigInteger that) {
            if (that.sign == 0 ) {
                return val;
            }
            if (val.sign == 0) {
                return BigInteger.ZERO;
            }
            if (val.equals(BigInteger.MINUS_ONE)) {
                return that.not();
            }
            if (that.equals(BigInteger.MINUS_ONE)){
                return BigInteger.ZERO;
            }
        
            //if val == that, return 0
        
           if (val.sign > 0) {
                if (that.sign > 0) {
                    return andNotPositive(val, that);
                } else {
                    return andNotPositiveNegative(val, that);
                        }
                    } else {
                if (that.sign > 0) {
                    return andNotNegativePositive(val, that);
                } else  {
                    return andNotNegative(val, that);
                }
            }
        }
    
        /** @return sign = 1, magnitude = val.magnitude & ~that.magnitude*/
        internal static BigInteger andNotPositive(BigInteger val, BigInteger that) {
            // PRE: both arguments are positive
            int []resDigits = new int[val.numberLength];
        
            int limit = java.lang.Math.min(val.numberLength, that.numberLength);
            int i;
            for (i = val.getFirstNonzeroDigit(); i < limit; i++) {
                resDigits[i] = val.digits[i] & ~that.digits[i];
            }
            for ( ; i < val.numberLength; i++) {
                resDigits[i] = val.digits[i];
            }
        
            BigInteger result = new BigInteger(1, val.numberLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = 1, magnitude = positive.magnitude & ~(-negative.magnitude)*/
        internal static BigInteger andNotPositiveNegative(BigInteger positive, BigInteger negative) {
            // PRE: positive > 0 && negative < 0
            int iNeg = negative.getFirstNonzeroDigit();
            int iPos = positive.getFirstNonzeroDigit();
        
            if (iNeg >= positive.numberLength) {
                return positive;
            }
        
            int resLength = java.lang.Math.min(positive.numberLength, negative.numberLength);
            int []resDigits = new int[resLength];
        
            // Always start from first non zero of positive
            int i = iPos;
            for ( ; i < iNeg; i++) {
                // resDigits[i] = positive.digits[i] & -1 (~0)
                resDigits[i] = positive.digits[i];
            }
            if (i == iNeg) {
                resDigits[i] = positive.digits[i] & (negative.digits[i] - 1);
                i++;
            }
            for ( ; i < resLength; i++) {
                // resDigits[i] = positive.digits[i] & ~(~negative.digits[i]);
                resDigits[i] = positive.digits[i] & negative.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = -1, magnitude = -(-negative.magnitude & ~positive.magnitude)*/
        internal static BigInteger andNotNegativePositive(BigInteger negative, BigInteger positive) {
            // PRE: negative < 0 && positive > 0
            int resLength;
            int [] resDigits;
            int limit;
            int digit;
        
            int iNeg = negative.getFirstNonzeroDigit();
            int iPos = positive.getFirstNonzeroDigit();
        
            if (iNeg >= positive.numberLength) {
                return negative;
            }
        
            resLength = java.lang.Math.max(negative.numberLength, positive.numberLength);
            int i = iNeg;
            if (iPos > iNeg) {
                resDigits = new int[resLength];
                limit = java.lang.Math.min(negative.numberLength, iPos);
                for ( ; i < limit; i++) {
                    // 1st case:  resDigits [i] = -(-negative.digits[i] & (~0))
                    // otherwise: resDigits[i] = ~(~negative.digits[i] & ~0)  ;
                    resDigits[i] = negative.digits[i];
                }
                if (i == negative.numberLength) {
                    for (i = iPos; i < positive.numberLength; i++) {
                        // resDigits[i] = ~(~positive.digits[i] & -1);
                        resDigits[i] = positive.digits[i];
                    }
                }
            } else {
                digit = -negative.digits[i] & ~positive.digits[i];
                if (digit == 0) {
                    limit = java.lang.Math.min(positive.numberLength, negative.numberLength);
                    for (i++; i < limit && (digit = ~(negative.digits[i] | positive.digits[i])) == 0; i++)
                        ; // digit = ~negative.digits[i] & ~positive.digits[i]
                    if (digit == 0) {
                        // the shorter has only the remaining virtual sign bits
                        for ( ; i < positive.numberLength && (digit = ~positive.digits[i]) == 0; i++)
                            ; // digit = -1 & ~positive.digits[i]
                        for ( ; i < negative.numberLength && (digit = ~negative.digits[i]) == 0; i++)
                            ; // digit = ~negative.digits[i] & ~0
                        if (digit == 0) {
                            resLength++;
                            resDigits = new int[resLength];
                            resDigits[resLength - 1] = 1;
                        
                            BigInteger result = new BigInteger(-1, resLength, resDigits);
                            return result;
                        }
                    }
                }
                            resDigits = new int[resLength];
                resDigits[i] = -digit;
                i++;
                        }
        
            limit = java.lang.Math.min(positive.numberLength, negative.numberLength);
            for ( ; i < limit; i++) {
                //resDigits[i] = ~(~negative.digits[i] & ~positive.digits[i]);
                resDigits[i] = negative.digits[i] | positive.digits[i];
            }
            // Actually one of the next two cycles will be executed
            for ( ; i < negative.numberLength; i++) {
                resDigits[i] = negative.digits[i];
                    }
            for ( ; i < positive.numberLength; i++) {
                resDigits[i] = positive.digits[i];
            }
        
            BigInteger result1 = new BigInteger(-1, resLength, resDigits);
            return result1;
                }
    
        /** @return sign = 1, magnitude = -val.magnitude & ~(-that.magnitude)*/
        internal static BigInteger andNotNegative(BigInteger val, BigInteger that) {
            // PRE: val < 0 && that < 0
            int iVal = val.getFirstNonzeroDigit();
            int iThat = that.getFirstNonzeroDigit();
        
            if (iVal >= that.numberLength) {
                return BigInteger.ZERO;
            }
        
            int resLength = that.numberLength;
            int[] resDigits = new int[resLength];
            int limit;
            int i = iVal;
            if (iVal < iThat) {
                // resDigits[i] = -val.digits[i] & -1;
                resDigits[i] = -val.digits[i];
                limit = java.lang.Math.min(val.numberLength, iThat);
                for (i++; i < limit; i++) {
                    // resDigits[i] = ~val.digits[i] & -1;
                    resDigits[i] = ~val.digits[i];
                }
                if (i == val.numberLength) {
                    for ( ; i < iThat; i++) {
                        // resDigits[i] = -1 & -1;
                        resDigits[i] = -1;
                    }
                    // resDigits[i] = -1 & ~-that.digits[i];
                    resDigits[i] = that.digits[i] - 1;
            } else {
                    // resDigits[i] = ~val.digits[i] & ~-that.digits[i];
                    resDigits[i] = ~val.digits[i] & (that.digits[i] - 1);
                }
            } else if (iThat < iVal ) {
                // resDigits[i] = -val.digits[i] & ~~that.digits[i];
                resDigits[i] = -val.digits[i] & that.digits[i];
            } else {
                // resDigits[i] = -val.digits[i] & ~-that.digits[i];
                resDigits[i] = -val.digits[i] & (that.digits[i] - 1);
                }
        
            limit = java.lang.Math.min(val.numberLength, that.numberLength);
            for (i++; i < limit; i++) {
                // resDigits[i] = ~val.digits[i] & ~~that.digits[i];
                resDigits[i] = ~val.digits[i] & that.digits[i];
            }
            for ( ; i < that.numberLength; i++) {
                // resDigits[i] = -1 & ~~that.digits[i];
                resDigits[i] = that.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }

        /** @see BigInteger#or(BigInteger) */
        internal static BigInteger or(BigInteger val, BigInteger that) {
            if (that.equals(BigInteger.MINUS_ONE) || val.equals(BigInteger.MINUS_ONE)) {
                return BigInteger.MINUS_ONE;
            }
            if (that.sign == 0) {
                return val;
            }
            if (val.sign == 0) {
                return that;
            }

                        if (val.sign > 0) {
                if (that.sign > 0) {
                    if (val.numberLength > that.numberLength) {
                        return orPositive(val, that);
                        } else {
                        return orPositive(that, val);
                        }
                    } else {
                    return orDiffSigns(val, that);
                }
                        } else {
                if (that.sign > 0) {
                    return orDiffSigns(that, val);
                } else if (that.getFirstNonzeroDigit() > val.getFirstNonzeroDigit()) {
                    return orNegative(that, val);
                } else {
                    return orNegative(val, that);
                        }
                    }
                }
    
        /** @return sign = 1, magnitude = longer.magnitude | shorter.magnitude*/
        internal static BigInteger orPositive(BigInteger longer, BigInteger shorter) {
            // PRE: longer and shorter are positive;
            // PRE: longer has at least as many digits as shorter
            int resLength = longer.numberLength;
            int[] resDigits = new int[resLength];
        
            int i = java.lang.Math.min(longer.getFirstNonzeroDigit(), shorter.getFirstNonzeroDigit());
            for (i = 0; i < shorter.numberLength; i++) {
                resDigits[i] = longer.digits[i] | shorter.digits[i];
            }
            for ( ; i < resLength; i++) {
                resDigits[i] = longer.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            return result;
        }
    
        /** @return sign = -1, magnitude = -(-val.magnitude | -that.magnitude) */
        internal static BigInteger orNegative(BigInteger val, BigInteger that){
            // PRE: val and that are negative;
            // PRE: val has at least as many trailing zeros digits as that
            int iThat = that.getFirstNonzeroDigit();
            int iVal = val.getFirstNonzeroDigit();
            int i;
        
            if (iVal >= that.numberLength) {
                return that;
            }else if (iThat >= val.numberLength) {
                return val;
            }
        
            int resLength = java.lang.Math.min(val.numberLength, that.numberLength);
            int[] resDigits = new int[resLength];
        
            //Looking for the first non-zero digit of the result
            if (iThat == iVal) {
                resDigits[iVal] = -(-val.digits[iVal] | -that.digits[iVal]);
                i = iVal;
            } else {
                for (i = iThat; i < iVal; i++) {
                    resDigits[i] = that.digits[i];
                }
                resDigits[i] = that.digits[i] & (val.digits[i] - 1);
            }
        
            for (i++; i < resLength; i++) {
                resDigits[i] = val.digits[i] & that.digits[i];
            }
        
            BigInteger result = new BigInteger(-1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = -1, magnitude = -(positive.magnitude | -negative.magnitude) */
        internal static BigInteger orDiffSigns(BigInteger positive, BigInteger negative){
            // Jumping over the least significant zero bits
            int iNeg = negative.getFirstNonzeroDigit();
            int iPos = positive.getFirstNonzeroDigit();
            int i;
            int limit;
        
            // Look if the trailing zeros of the positive will "copy" all
            // the negative digits
            if (iPos >= negative.numberLength) {
                return negative;
            }
            int resLength = negative.numberLength;
            int[] resDigits = new int[resLength];
        
            if (iNeg < iPos ) {
                // We know for sure that this will
                // be the first non zero digit in the result
                for (i = iNeg; i < iPos; i++) {
                resDigits[i] = negative.digits[i];
                }
            } else if (iPos < iNeg) {
                i = iPos;
                resDigits[i] = -positive.digits[i];
                limit = java.lang.Math.min(positive.numberLength, iNeg);
                for(i++; i < limit; i++ ) {
                    resDigits[i] = ~positive.digits[i];
                }
                if (i != positive.numberLength) {               
                    resDigits[i] = ~(-negative.digits[i] | positive.digits[i]);                
                } else{
                      for (; i<iNeg; i++) {
                          resDigits[i] = -1;
                      }
                      // resDigits[i] = ~(-negative.digits[i] | 0);
                      resDigits[i] = negative.digits[i] - 1;
                }
                i++;
            } else {// iNeg == iPos
                // Applying two complement to negative and to result
                i = iPos;
                resDigits[i] = -(-negative.digits[i] | positive.digits[i]);
                i++;
            }
            limit = java.lang.Math.min(negative.numberLength, positive.numberLength);
            for (; i < limit; i++) {
                // Applying two complement to negative and to result
                // resDigits[i] = ~(~negative.digits[i] | positive.digits[i] );
                resDigits[i] = negative.digits[i] & ~positive.digits[i];
            }
            for( ; i < negative.numberLength; i++) {
                resDigits[i] = negative.digits[i];
            }
        
            BigInteger result = new BigInteger(-1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }

        /** @see BigInteger#xor(BigInteger) */
        internal static BigInteger xor(BigInteger val, BigInteger that) {
            if (that.sign == 0) {
                return val;
            }
            if (val.sign == 0) {
                return that;
            }
            if (that.equals(BigInteger.MINUS_ONE)) {
                return val.not();
            }
            if (val.equals(BigInteger.MINUS_ONE)) {
                return that.not();
            }
        
            if (val.sign > 0) {
                if (that.sign > 0) {
                    if (val.numberLength > that.numberLength) {
                        return xorPositive(val, that);
                    } else {
                        return xorPositive(that, val);
                    }
                } else {
                    return xorDiffSigns(val, that);
                }
            } else {
                if (that.sign > 0) {
                    return xorDiffSigns(that, val);
                } else if (that.getFirstNonzeroDigit() > val.getFirstNonzeroDigit()) {
                    return xorNegative(that, val);
                } else {
                    return xorNegative(val, that);
                }
            }
        }
    
        /** @return sign = 0, magnitude = longer.magnitude | shorter.magnitude */
        internal static BigInteger xorPositive(BigInteger longer, BigInteger shorter) {
            // PRE: longer and shorter are positive;
            // PRE: longer has at least as many digits as shorter
            int resLength = longer.numberLength;
            int[] resDigits = new int[resLength];
            int i = java.lang.Math.min(longer.getFirstNonzeroDigit(), shorter.getFirstNonzeroDigit());
            for ( ; i < shorter.numberLength; i++) {
                resDigits[i] = longer.digits[i] ^ shorter.digits[i];
            }
            for( ; i < longer.numberLength; i++ ){
                resDigits[i] = longer.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = 0, magnitude = -val.magnitude ^ -that.magnitude */
        internal static BigInteger xorNegative(BigInteger val, BigInteger that){
            // PRE: val and that are negative
            // PRE: val has at least as many trailing zero digits as that
            int resLength = java.lang.Math.max(val.numberLength, that.numberLength);
            int[] resDigits = new int[resLength];
            int iVal = val.getFirstNonzeroDigit();
            int iThat = that.getFirstNonzeroDigit();
            int i = iThat;
            int limit;
        
        
            if (iVal == iThat) {
                resDigits[i] = -val.digits[i] ^ -that.digits[i];
            } else {
                resDigits[i] = -that.digits[i];
                limit = java.lang.Math.min(that.numberLength, iVal);
                for (i++; i < limit; i++) {
                    resDigits[i] = ~that.digits[i];
                }
                // Remains digits in that?
                if (i == that.numberLength) {
                    //Jumping over the remaining zero to the first non one
                    for ( ;i < iVal; i++) {
                        //resDigits[i] = 0 ^ -1;
                        resDigits[i] = -1;
                    }
                    //resDigits[i] = -val.digits[i] ^ -1;
                    resDigits[i] = val.digits[i] - 1;
                } else {
                    resDigits[i] = -val.digits[i] ^ ~that.digits[i];
                }
            }
        
            limit = java.lang.Math.min(val.numberLength, that.numberLength);
            //Perform ^ between that al val until that ends
            for (i++; i < limit; i++) {
                //resDigits[i] = ~val.digits[i] ^ ~that.digits[i];
                resDigits[i] = val.digits[i] ^ that.digits[i];
            }
            //Perform ^ between val digits and -1 until val ends
            for ( ; i < val.numberLength; i++) {
                //resDigits[i] = ~val.digits[i] ^ -1  ;
                resDigits[i] = val.digits[i] ;
            }
            for ( ; i < that.numberLength; i++) {
                //resDigits[i] = -1 ^ ~that.digits[i] ;
                resDigits[i] = that.digits[i];
            }
        
            BigInteger result = new BigInteger(1, resLength, resDigits);
            result.cutOffLeadingZeroes();
            return result;
        }
    
        /** @return sign = 1, magnitude = -(positive.magnitude ^ -negative.magnitude)*/
        internal static BigInteger xorDiffSigns(BigInteger positive, BigInteger negative){
            int resLength = java.lang.Math.max(negative.numberLength, positive.numberLength);
            int[] resDigits;
            int iNeg = negative.getFirstNonzeroDigit();
            int iPos = positive.getFirstNonzeroDigit();
                int i;
            int limit;
        
            //The first
            if (iNeg < iPos) {
                resDigits = new int[resLength];
                i = iNeg;
                //resDigits[i] = -(-negative.digits[i]);
                resDigits[i] = negative.digits[i];
                limit = java.lang.Math.min(negative.numberLength, iPos);
                //Skip the positive digits while they are zeros
                for (i++; i < limit; i++) {
                    //resDigits[i] = ~(~negative.digits[i]);
                    resDigits[i] = negative.digits[i];
                }
                //if the negative has no more elements, must fill the
                //result with the remaining digits of the positive
                if (i == negative.numberLength) {
                    for ( ; i < positive.numberLength; i++) {
                        //resDigits[i] = ~(positive.digits[i] ^ -1) -> ~(~positive.digits[i])
                        resDigits[i] = positive.digits[i];
                    }
                }
            } else if (iPos < iNeg) {
                resDigits = new int[resLength];
                i = iPos;
                //Applying two complement to the first non-zero digit of the result
                resDigits[i] = -positive.digits[i];
                limit = java.lang.Math.min(positive.numberLength, iNeg);
                for (i++; i < limit; i++) {
                    //Continue applying two complement the result
                    resDigits[i] = ~positive.digits[i];
                }
                //When the first non-zero digit of the negative is reached, must apply
                //two complement (arithmetic negation) to it, and then operate
                if (i == iNeg) {
                    resDigits[i] = ~(positive.digits[i] ^ -negative.digits[i]);
                    i++;
                } else {
                    //if the positive has no more elements must fill the remaining digits with
                    //the negative ones
                    for ( ; i < iNeg; i++) {
                        // resDigits[i] = ~(0 ^ 0)
                        resDigits[i] = -1;
                    }
                    for ( ; i < negative.numberLength; i++) {
                        //resDigits[i] = ~(~negative.digits[i] ^ 0)
                        resDigits[i] = negative.digits[i];
                    }
                }
                    } else {
                int digit;
                //The first non-zero digit of the positive and negative are the same
                i = iNeg;
                digit = positive.digits[i] ^ -negative.digits[i];
                if (digit == 0) {
                    limit = java.lang.Math.min(positive.numberLength, negative.numberLength);
                    for (i++; i < limit && (digit = positive.digits[i] ^ ~negative.digits[i]) == 0; i++)
                        ;
                    if (digit == 0) {
                        // shorter has only the remaining virtual sign bits
                        for ( ; i < positive.numberLength && (digit = ~positive.digits[i]) == 0; i++)
                            ;
                        for ( ; i < negative.numberLength && (digit = ~negative.digits[i]) == 0; i++)
                            ;
                        if (digit == 0) {
                            resLength = resLength + 1;
                            resDigits = new int[resLength];
                            resDigits[resLength - 1] = 1;
                        
                            BigInteger result = new BigInteger(-1, resLength, resDigits);
                            return result;
                    }
                }
            }
                resDigits = new int[resLength];
                resDigits[i] = -digit;
                i++;
            }
        
            limit = java.lang.Math.min(negative.numberLength, positive.numberLength);
            for ( ; i < limit; i++) {
                resDigits[i] = ~(~negative.digits[i] ^ positive.digits[i]);
            }
            for ( ; i < positive.numberLength; i++) {
                // resDigits[i] = ~(positive.digits[i] ^ -1)
                resDigits[i] = positive.digits[i];
            }
            for ( ; i < negative.numberLength; i++) { 
                // resDigits[i] = ~(0 ^ ~negative.digits[i])
                resDigits[i] = negative.digits[i];
            }
        
            BigInteger result1 = new BigInteger(-1, resLength, resDigits);
            result1.cutOffLeadingZeroes();
            return result1;
        }
    }
}
